import React, { Component } from 'react'

export default class Child extends Component {
  state = {
    count: 0,
  }
  // 实例方法
  changeCount = (num) => {
    this.setState({ count: this.state.count + num })
  }
  render() {
    return <div>Child: {this.state.count}</div>
  }
}
